Something in the air: Jenny Seagrove, David Bamber and Jane Horrocks in Absurd Person Singular at the Garrick, London, in 2007. Photograph: Tristram Kenton

"It is difficult to find a bright moment in 1972," wrote the historian Christopher Lee in This Sceptred Isle. And he had a point. Few people think back fondly to a year that saw mass unemployment, a miners' strike that led to blackouts lasting nine hours a day, violence on the picket lines and the declaration of a state of emergency. Add to that outbreaks of terrorism in just about every major European state, and it would seem to be a year to forget.

If one looks for any compensating cheer on the cultural front, it might be in the fact that a new play by Alan Ayckbourn, Absurd Person Singular, opened at the Library Theatre (now the Stephen Joseph Theatre) in Scarborough in June. Ayckbourn was already established as a master of comic ingenuity through two hit plays, Relatively Speaking and How the Other Half Loves. In his new play he seemed to have gone even further in his blend of comedy and tragedy. Set on three successive Christmas Eves in three different households, the play, which moved to London in the summer of 1973, quickly became famous for its middle act: one in which the wife of a philandering architect tries to kill herself in her own kitchen only to be thwarted by her guests, who repeatedly misinterpret her actions. Despair mixed with hilarity in a way that made one think back to Chekhov in Uncle Vanya or Nikolai Erdman in The Suicide.

But with Ayckbourn himself now revivingAbsurd Person Singular, in a 40th anniversary production that opens in Scarborough before moving to Chichester, it may be time to re-assess the play's significance. It didn't just mark a personal breakthrough for Ayckbourn, in that he pushed the formal boundaries to the limit, it also confirmed him as one of the most perceptive social commentators in British theatre. To understand that, one has to think back to what Britain was like in the early 70s. Amid the industrial strife of the Heath years, there was an artificial mini-boom fuelled, as Andy Beckett observes in When the Lights Went Out, by speculation and one-off government initiatives. It proved to be unsustainable but between mid-1971 and mid-1973 house prices rose by almost three-quarters. During the 70s, property became the path to individual progress.

This is precisely what Ayckbourn shows, while also making us laugh, in Absurd Person Singular. Without giving too much away, the play shows the unstoppable rise of Sidney Hopcroft. He starts out as a small tradesman nervously entertaining, along with his mercilessly bullied wife, a toffish bank manager and a middle-class architect. By the second act he is "up and coming", and even the once-successful architect, in trouble with a Super Shopperdrome that has run disastrously over budget, is being pushed by his wife into hitching his wagon to Hopcroft's rising star. But it is in the third act that Ayckbourn reveals the reversal of social values. It is set in the unheated Victorian kitchen of the gloomy bank manager, whose wife has sunk into a permanent alcoholic stupor. The roof has literally fallen in on the architect's Shopperdrome, thereby destroying his professional reputation. Only Hopcroft is thriving as a local property developer, although as the architect sharply remarks, "half his tenants are asking to be rehoused and they haven't even moved in yet".

At the time the play opened, the only critic to grasp that Ayckbourn was infinitely more than a boulevard entertainer was the late Ronald Bryden. Reviewing Absurd Person Singular in Plays and Players, he wrote: "Ayckbourn is a political propagandist who works on people's minds without letting them know he's doing it or drawing attention to his own rectitude." Speaking specifically of this play, he went on: "The final scene, in which Sidney forces the bank manager and architect to play the humiliating party games they evaded at his party two years before, is as cuttingly vivid an image of the Poulson affair as any British playwright is likely to offer us."

The significance of the reference to John Poulson is that he was an architect whose corrupt association with politicians led to his own imprisonment, as well as that of the Labour boss of Newcastle council, T Dan Smith, and the resignation of the Tory home secretary, Reginald Maudling. Ayckbourn's play, in short, reflects the squalor and seediness of the new enterprise culture.

I'm not sure I'd go as far as Bryden in calling Ayckbourn a propagandist. But, over the years, he has shown an underrated ability to take the national temperature. He deals a lot with marriage, male-female relations and the strains of suburban life in a way that led a German critic to dub him "the Molière of the middle classes". At the same time his sharp social antennae are always in evidence. Way Upstream (1981), set on a floating cabin cruiser, was originally notorious as the play that flooded the stage of the National's Lyttelton Theatre. More importantly, the play uses the boat as a metaphor for an early-80s England in which the voices of moderation and reason were being drowned out by an ugly extremism.

Though it was never one of his most popular or successful works, A Small Family Business, which opened at the National's Olivier Theatre in 1987, was what Ayckbourn's biographer, Paul Allen, has justly called "the central political play of the decade". Certainly I can't think of any play that pins down so accurately the paradox at the heart of Thatcherism: the simultaneous celebration of traditional family values and the sanctification of individual greed. You can't, Ayckbourn implies, have it both ways. And he explores this through the dilemma confronting Jack McCracken, superbly played at the National by Michael Gambon.

On inheriting the family furniture business, honest Jack resolves to show zero tolerance to petty theft, whether it be fiddling expenses or pinching paper-clips. But when he finds his daughter accused of shoplifting, he tries to buy off a slimy private investigator. And when he discovers that the whole family income depends on illegal furniture-flogging, he is driven into the role of reluctant bagman. What you see, over two remorselessly brilliant acts, is Jack reduced to mafioso dealing and even contemplating murder in order to protect the family's interests. Without preaching or polemicising, Ayckbourn shows us how "corruption, mining all within, infects unseen", in a way that reminds one of JB Priestley's An Inspector Calls or Friedrich Dürrenmatt's anti-capitalist satire The Visit.

Even today Ayckbourn retains his sharp eye for the contradictions in our social and political system. His 75th and most recent play, Neighbourhood Watch, is a mercilessly funny exposé of all the Cameronian babble about the need for a vigorous communal response to our supposedly "broken society". It shows what can happen when law and order is left to a group of volunteer vigilantes – a crusading local regime, based on unflinching public morality and much lauded by the Daily Mail, turns increasingly malign and violent. As so often Ayckbourn seems to be following the example set by Ibsen in The Wild Duck and warning us that when well-meaning idealists come knocking at the door, it is best not to answer.

Ayckbourn himself, I suspect, would react with mild horror to the idea that he is a political dramatist. His plays seems to arise more from a sixth sense about what is wrong with our private relations or with the world at large and from the excitement of rising to some self-imposed technical challenge. But I still see his immense oeuvre as an anguished liberal's response to the injustice and cruelty of men towards women and to the rigidity of doctrinaires who seek to impose their values on the rest of us. Behind Ayckbourn the entertainer lurks the sharpest observer of human folly in modern British drama; and one who, through Absurd Person Singular, proves that 1972 may not have been so bad after all.